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CHAPTER 5 SAR FUNCTION
134
Figure 5-13. Transmit Queue Containing Interrupt Mask Packets
Packet descriptor #1 (IM = 1)
Vacant packet descriptor
Transmit queue
read pointer
Data buffer
Transmit queue
Data buffer
Data buffer
Data buffer
Packet descriptor #2 (IM = 1)
Packet descriptor #3 (IM = 0)
Packet descriptor #4 (IM = 1)
Packet descriptor #5 (IM = 1)
Packet descriptor #6 (IM = 0)
The host sets interrupt mask packets in packet descriptors #1, #2, #4, and #5. The
μ
PD98405 does
not inform the host of when it has transmitted packets #1 and #2. Once it has transmitted packet #3,
it informs the host by issuing an interrupt, and stores the relevant indication into the mailbox. Upon
being informed of the completion of the transmission of packet #3 by means of the indication, the
host releases the data buffers for packets #1, #2, and #3. In this way, it is possible to process more
than one complete packet through one transmission completion interrupt.
<6>
C10
This bit specifies whether a CRC-10 error detection code is inserted.
1
The
μ
PD98405 inserts a 10-bit CRC-10 error detection code in each cell.
C10
0
The
μ
PD98405 does not insert a CRC-10 code.
If this bit is set to "1," the
μ
PD98405 executes a CRC operation on the field having the payload part,
excluding the last 10 bits, and inserts the result at the end of the cell as a 10-bit CRC-10 error
detection code.
Figure 5-14. Inserting CRC-10
Header
5 bytes
Payload
46 bytes + 6 bits
CRC-10
10 bits